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Number of n X n binary matrices, symmetric about the diagonal and under 90-degree rotation, with no more than 1 one in any 2 X 2 subblock.
0

%I #5 Nov 25 2018 12:30:08

%S 1,2,1,3,2,9,3,28,9,137,28,811,137,6884,811,75303,6884,1133287,75303,

%T 22573092,1133287,608722751,22573092,21933950111,608722751,

%U 1064082678978,21933950111,69200610896639,1064082678978,6047740350081131,69200610896639

%N Number of n X n binary matrices, symmetric about the diagonal and under 90-degree rotation, with no more than 1 one in any 2 X 2 subblock.

%K nonn

%O 0,2

%A _R. H. Hardin_, Aug 09 2008